Re: PCI Clk Signal Track

yy7d6@xxxxxxxxxxxx wrote:
Hello i have a question about the PCI-33 Mhz Clk signal trace in a pcb,
i have found boards with somewhat zig-zag pci trace(CLK), what is the
reason for this?

here is a good picture to show what i mean:
http://www.dearhoney.idv.tw/MUSEUM/CMEDIA_CMI8738.jpg

In high speed design, it is sometimes necessary to match the length of
signal traces so that the signal edges occur in sync. For example, it
may be necessary to make ensure that the clock signal is in sync with
the data bus and that all data bus line transitions reach the receiver
at the same time. To accomplish this, many PCB tools will allow you to
add 'delay' to a line by putting in the "trombone" sections like appear
at the bottom of the picture you linked to. You may have also noticed
that these traces are rounded in the curves. This has the effect of
keeping the trace width constant to help control the characteristic
impedance of the line.

.

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